This invention relates to an ornamental alloy material, and more particularly to a nickel-chronium alloy including a predetermined amount of silver making it suitable for ornamental purpose, such as eye glass frames.
Stainless steel (AISI 304) and nickel silver are well known materials used for spectacle or glasses frames. However, these materials are not extremely well suited for such frames because of the color tones they exhibit. Stainless steel is darkish and exhibits a low light reflectivity. Nickel silver is reddish, because of inclusion of a large quantity of copper, and its color tone is quite different from that of platinum. Platinum is suitable for such frames and provides pleasing color tones, but it is very expensive material. Silver is also known as a material for these frames, but it is not entirely suitable because it presents strong white light due to its high light reflectivity.
Recently, nickel-chromium alloy has come to be widely used for ornamental purposes, including glass or spectacle frames because of its excellent corrosion resistance and white metallic gloss. Since the manufacturing of glasses parts requires very fine cutting and machining, fast-cutting material is needed. To realize such a fast-cutting material, nickel-chromium with the addition of silver was proposed. This conventional nickel-chromium with addition of silver was produced by adding 0.3-10 wt. % silver to nickel alloy including 5-20 wt. % chromium. This fast-cutting property is not achieved unless silver forms solid solution with either chromium or nickel. As observed through X-ray micro-analyzer techniques, the results of which are shown in FIG. 1, silver is globularly distributed within the material. The white spots are silver particles and this FIGURE shows conventional nickel-chromium alloy to which silver has been added. This conventional nickel-chromium alloy that includes silver was used for the exterior portions of glasses frames, such as around the rims, for the bridge and the side pieces.
However, in preparing the conventional nickel-chromium alloy with silver no thought was given to how the silver was added or distributed through the resulting alloy. Accordingly, that alloy was not satisfactory because its color tone is not exactly what is most desirable.